Just so you know, I am also Jesse Woody...it's funny how I publish on the main site as my real name, but then get to post in the WOD comments as my internet pseudonym :p
I would suggest building your jumping ability in this way:
1. Proper biomechanics- good form on the basics of the movements. This means a perfect squat, lunge etc. This assures a good base to build everything else from
2. A good base of strength- If you have access to weights, then you can get way ahead here. When the Bulgarians were using plymetrics for their Olympic track and weightlifting athletes in the 70's they suggested that you should posess a 2x bodyweight squat before starting. While this may be a bit more than necessary, the idea is sound. Even the most basic plyometric exercises expose your connective tissues to an extreme amount of force, and to top it off, these tissues strengthen slower than muscles, so you can be strong enough to really hurt yourself over time. I would suggest being comfortable with relatively heavy squats (at least 1.5x bodyweight) before jumping *pun* too far into a plyo program.
3. Slowly incorporating plyometrics into your program- I would start with some basics that are lower-impact such as box-jumps with a regular step off of the box, some small reactive jumps (stand on a step, hop backwards slightly towards the ground, as soon as your feet hit immediately explode back up via-calf muscle power) and jump squats. Perform them at relatively low reps with ample rest. This allows you to put 100% power into each movement which will ensure proper development of explosive traits within your muscles. Stop WAY before failure, as both strength and power are motor skills which are best trained when fresh. When I feature high-rep power-movements in the WOD, it's for the sake of these movement's ability to elicit a powerful conditioning response and to develop the power-endurance and stamina that is often required for Parkour. This IS NOT the best way to improve limit power if that is your main goal.
Stay at a relatively easy level for longer than you think you should. This will allow you to build up the tendon and ligament strength over time to handle the higher-impact movements and ensure injury-free training.
